Following the collision of the Indian plate with the Eurasia Continent at 45 Ma,th e Cenozoic volcanic activities of North Tibet show three tectonicmagmatic sub cy cles.Three corresponding volcanic subzones were formed,from South to North ,they are the Qiangtang(44～24 Ma) , Kunlun—Hohxil(19～7 Ma) and west Kunlun —Yumen (5 Ma) volcanic subzones. Each subcycle began with volcanic activiti es of high K alkalicalcic or shosernite seires, ended with alkali potassic volcanic acti vities and the appearance of plateau planation surfaces. The evolument of volca nic series is closely related transformation from the pulasting compression ,thicke ning to extension and slippery of the lithosphere in both time and space.